1. Technical Field
The present invention relates to a pluggable optical transceiver to be engaged with a cage arranged on a host board, for example, and more particularly to a stable engagement mechanism between an electric connector arranged in a cage and a plug of an optical transceiver.
2. Related Prior Art
The conventional structure known in this field includes the optical transceivers disclosed in U.S. Pat. No. 6,335,869 and U.S. Pat. No. 6,439,918. The optical transceivers described in these publications have a circuit board having a plug to be engaged with a connector on a host board, and a housing which contains this circuit board. The circuit board is positioned and fixed in the housing. On the other hand, a cage, into which the optical transceiver is to be inserted, is fixed on the host board, and the connector is fixed at the deep end of this cage on the host board. It is possible to transfer signals and/or electrical power between the host system and the optical transceiver by inserting the optical transceiver into the cage and engaging the plug of the optical transceiver with the connector. Therefore it is important to ensure the dimensional accuracy of the gap between the outer surface of the housing of the optical transceiver and the inner surface of the cage and to ensure the relative positional accuracy between the cage and the connector.
However, small deviation of relative positions between the connector and the cage sometimes causes unsuccessful engagement between the connector and the plug. For example, upon the engagement between the conventional connector and plug, the gap between the outer surface of the housing of the transceiver and the inner surface of the cage is set to such dimensions that the plug is appropriately guided within the width of the connector. If this gap is set large, the plug comes off the plug-engaging part of the connector. In that situation, the plug and the connector is unable to smoothly engage to each other even if the transceiver is pushed into the cage. This gap is ruled within 0.7 mm by the standard, i.e., MSA (Multi-source Agreement).
This condition for the engagement is not met when deviation occurs in the relative positional relationship between the connector and the cage, too. That is, even if the gap ruled by the aforementioned MSA is correctly set, the plug may touch the edge of the connector, i.e., portions other than the plug-engaging part of the connector, so as to hinder the engagement between the connector and the plug when there is even a small deviation of 0.17 mm in the relative positions between the connector and the cage.
The cage is fabricated by cutting and bending a single metal plate. With repeated insertions and extractions of the transceiver, the cage can be deformed by stress applied during the insertions and extractions, and thus the plug and the connector can fail to engage. Furthermore, with a multi-cage structure in which a plurality of cages are disposed adjacent to each other, when optical transceivers are inserted into the adjacent cages, a partition between the cages can be deformed, and the plug and the connector can fail to engage.
The present invention has been accomplished in order to solve the problem as described above, and an object of the invention is to provide an optical transceiver enabling a plug on a circuit board to be readily engaged with a connector.